Your Atwood GC10A-3E is indeed a electic & gas water heater
BUT the electric uses it's own separate 120V AC set of t-stat/ECO. They are located on backside of water heater tank with the electric element
The gas uses it's own separate 12V DC set of t-stat/ECO and they are located on front in the outside compartment
Both sets are fixed temp
T-stat OPENS at 140*F (closes for refire at 110*F)
ECO (Energy Cut Off--High temp) OPENS at 180*F
Warm water on electric AND propane..then either water heater bypass valve is open/leaking thru (as suggested)
OR you have a shower still on (Hot/Cold Knobs open) and turned off at handle (allows hot/cold to mix inside the shower faucet which then results in warm water in hot lines)
FYI....Mixer Valves used on 'EXT' models (GE9-EXT or GE16-EXT)
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31